Alkyl aryl sulfonate detergent composition



April 7, 1953 J. c. SHOWALTER ET AL 2,534,240

ALKYL ARYL SULFONATE DETERGENT COMPOSITIQN Filed July 9, 1949 COMPOSITION a O 0 I5 DETERGENT CONCENTRATION (Wt lo IN SOLUTION) com POSITION "A"\/ o o o O O o no qm N T O N I INVENTORS.

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Patented Apr. 7, 1953 ALKYL ARYL SULFONATE DETERGENT COMPOSITION Jere C. Showalter, Baytown, and Albert J. Shmidl, Houston, Tex., assignors, by mesne assignments, to Standard Oil Development Company, Elizabeth, N. J., a corporation of Delaware Application July 9, 1949, Serial No. 103,854

The present invention is directed to a new composition having detergency properties.

Prior to the present invention, it has been known to employas detergents alkylated derivatives of aryl sulfonic acids as alkali metal salts thereof. Thus, in U. S. 2,161,174, Kyrides teaches Claims. (Cl. 252-161) naphthalene or the like, which is then sulfonated to form the sulfonic acid, following which the sodium salt is formed. The compounds men-- tioned by Kyrides are quite active as detergents and have achieved considerable utility in industry.

The preparation of similar alkali metal alkyl aryl sulfonate detergents by a similar chemical reaction is taught by Flett in U. S. 2,387,572. Flett chooses to identify these compounds, which contain alkyl side chains derived from kerosene, as keryl aryl sulfonates. This terminology is adopted for use herein, for convenience in differentiating between the long chain alkyl aryl sulfonates of known detergent quality and the xylene sulfonates employed in our invention. It is understood that the term keryl aryl sulfonates, as used herein, comprises not only compounds whose alkyl chain is derived from ,ker o sene itself, but also those compounds of "like chemical structure and formula whose alkyl chain is obtained from other known sources, such as olefin polymers and the like. The alkyl chain in these compounds may contain from nine to sixteen carbon atoms, that being the rangenor mally met with in kerosene.

It is also known, and has been described, i; e. in the above mentioned patent to Flett, that excellent detergent compositions may be prepared :by admixing 40 to 65 weight per cent of a water soluble salt, such as analkali sulfate, with 60 to 35 weight per cent of a keryl aryl sulfonate.

, It is well known that keryl aryl sulfonates, in order tobe useful as detergents, must be prepared from selected feed stocks in carefully controlled reactions; thus the minimum cost at which these compounds may be prepared is fixed by the conditions required in their preparation. On the other'hand, alkali metal xylene sulfonates are frequently met with as by-products, or contained in wasteproducts, in ordinary petroleum refinery practice. For example, they may be contained neutralization of acid treated aromatic petroleum distillate fractions, usually those which have: previously been subjected to a hydrocarbon con-:

version operation, such as reforming. In many cases the xylene sulfonates are not recovered, but instead are discarded with the spent caustic.

It is also well known that the alkali metal xylene sulfonates, although they are good wetting agents, are useless as detergents.

It is the main object of the present invention to provide an improved composition'having detergency characteristics which comprises a substantial portion of xylene sulfonates'.

Another object of the present invention is to provide a detergent composition comprising a lower amount of active detergent compound than heretofore required, together with'a substantial amount of xylene sulfonates and a substantial amount of a water soluble inorganic salt.

Another object of our invention isto provide a composition comprising both xylene sulfonates and keryl aryl sulfonates in such a manner that the synergistic effect exerted by these compounds upon one another will permit theuse of substantially lower concentrations of keryl aryl sulfonate than would be required to provide a desired detergency in the absence of xylene sulfonates. Y The objects of the present invention may be achieved by forming a'composition comprising a major amount of a mixture of alkali metal salts of xylene sulfonic acids and a water soluble salt having an inorganic cation, such as illustrated by the Water soluble sulfates, sulfites, thiosulfates, chlorides, dihydrogen phosphates, borates, and acetates, and a minor amount of alkali metalsalts of keryl aryl sulfonic acids. Thus the present invention may be described briefly as involving a composition comprising a mixture of a sodium salt of xylene sulfonic acid and a Water soluble inorganic salt as illustrated above in a major amount of a sodium salt of a keryl aryl sulfonic acid, the amount of the salt of the keryl aryl sulfonic acid being less than the amount of the salt of xylene sulfonic acidin the composition.

The sodium salts of the xylene sulfonicgacids' may be prepared in the conventional manner by sulfonatingxylenes with concentrated sulfuric acid, contacting the sulfonated xylenes with an aqueous solution of sodium hydroxide, and finally evaporating to dryness; If a selected excess of sulfuric acid is employed, the solid residue which is obtained consists of a mixture of sodium xylene sulfonates and sodium sulfate, which is desirable for use in the compositions of our invention. n the other hand, sodium xylene sulfonates may be recovered from spent caustic which has been previously employed in neutralizing sulfuric-acid treated, xylene-containing hydrocarbon fractions, such. as hydroformed naphthenic gasolineor kerosene-range distillates or the like, by neutralizing the remaining free alkali with a small amount of an inorganic acid, such .as sulfuric acid, and evaporating the product to dryness. The residue will contain sodium Xylene sulfonates and sodium sulfate, usually in the approximate weight ratio of 60:40. Since meta xylene is sulfonated more readily than; the other isomers, sulfonated meta xylene. is the predominant constituent of the resulting product.- The mixture of sodium xylene sulfonates and sodium sulfate prepared as described above is useful as a wetting agent but has little utility as. a. detergent since it exhibits none of the characteristics of a detergent.

The alkali metal saltv of a keryl aryl sulfonic acid. employed in our invention may be prepared as described in the aforesaid patent, U. S. 2,161,174 to. Kyrides, or may bev obtained separately or admixed with alkali metal sulfate as describedby Flettin U. S. 2,387,572, or by other methods known to the art.

The alkali. metal salt of the xylene sulfonic acid employed in our invention. is preferably a.

sodium salt, but the potassium and lithium salts may be used in lieu. of the sodium salt although the latter. is preferred. The xylene which is suls fonated and neutralized. with the alkali metal.

hydroxide may be ortho-,. meta-, or para-xylene, or a mixture thereof. Meta-xylene may be sulfonated with. an excess of concentrated. sulfuric I acid. of at least 98 weight per cent concentration and the sulfonated. xylene contacted with an aqueous solution of sodium hydroxide, which may be of 20 B. gravity, to form a. mixture of form. a mixture of sodium meta-xylene sulfonate and sodium sulfate which may be heated to remove water by evaporation and the mixture then employed in the. composition of the present in vention-..

This invention will be further illustrated by comparative tests carried out on a composition according to this invention and on a conventional detergent.- composition. The compositions were dissolvedin water, in varying concentrations, and tested for detergency characteristics in a. launderometer suchas. described inthe article by Bacon and Smith, Industrial and Engineering Chemistry, vol. 40,, No. 12, pages 2361-2370, December 1948. The launderometer was operated. at. 4'2: revolutions per minute, and. 15 steel ballsv were employed in the tests. The test consisted, briefly, of washing soiled swatches of unsized, bleached. white, cotton muslin. of about 80 by 80 thread, count. The muslin was soiled with a standard soil-ing solution comprising 216: grams of extra white petrolatum and 108 grams of lamp black in. [8 liters of carbontetrachloride. The soiled swatches were passed through the soiling solution in a soiling machine, dried in air, and. aged for 5. days. before use. The aged swatches... were. then placed. in a. bottle containing 200. cc. of. a solution; of varying concentrations of detergent. in tap water of about 2 3 P. R. M. hardness- The l'aunderometer was operated at 42 revolutions per minute: for 25 minutes at 120- F., following which. the machine was stopped. and the volume of the suds in each jar,

initially and after minutes, was-noted. The

' page 207 and following, 1941.

washed swatches were removed from the jars. drained without squeezing or working, and then rinsed with tap water and dried. After drying, the Hunter value, which is the fraction of light reflected from the laundered swatches, measured on a Hunter reflectometer, was determined in accordance with the method described by Hunter in Paint Varnish Production Manager, vol 21, The Hunter value being indicative of the fraction of light reflected from a sample, a relatively high Hunter value is indicative of good detergent action bythe solution tested. A blank was run by subjectinga sample immersed in water containing no added. detergent composition to the procedure described above.

A soil removal factor was calculated for each test by subtracting the average Hunter value" obtained from the blank runs from the Hunter value of the cloth washed in the test solution, and multiplying the difference obtained by a factor of 1,000. A high soil removal. factor is indicative of good detergent action of thetest solution. It is not unusual for the soil removal factor to be a negative value where a test solution has substantially no detergency.

In order to determine the detergent action of a composition prepared according to my invention, tests. were. made on the following three compositions:

Compos' ion A was. a commercial, household detergent whose. active ingredient is a keryl aryl suifonate. This detergent consists of approximately 40 weight per cent of the keryl aryl sulionate and approximately 60% of sodium sulfate.

Composition. B. consisted of 60 weight per cent sodium xylene sulfonates, preponderantly the sulfonate cf meta-xylene, admixed with 40% of sodium sulfate.

Composition C, was prepared by admixing 4 parts by weight of composition B with 1 part by weight of composition A. Thus, composition 0 consisted of. 8% of sodium keryl aryl sulfonate, 48% of sodium xylene sulfonates and 44% of sodium' sulfate.

The detergency value of these compositions was tested by the above described procedure, employing a launderometer and Hunter reflectometer. The resultsof these tests are presented in the table.

Table.

Concen- Suds, Inches Soil Composition gat z fi Egg? Removal cent Initial 5.10m Fact For ease of interpretation, the results of these tests have been plotted: graphically in the sole figure of. the drawing which presents a plot of soil removal factor against the concentration of detergent in the solution tested; It is seen that in. the case of. composition. A the. soil. re.- moval factor increases in a linear relationship with detergent concentration I over the range tested. It also seen that compositionB has soil removal factor corresponding to a given concentration of composition C in the test solution, the weight per cent of each component making up composition is multiplied by the soil removal factor corresponding to that concentration, as read from the graphs.

Thus, for 0.30 weight per cent of composition C, the concentration of composition A (which makes up 20% of composition C) would be 0.20 0.30=0.06%, and similarly the concentration of composition B=0.24%. The soil removal factor for 0.06% of composition A, as read from the curve therefor, is +14 and that for 0.24% of composition B is +5. The total, or calculated expected soil removal factor of 0.30 weight per cent of composition C, therefore, is +19. Since the experimentally determined soil removal factor of an 0.30% solution of composition C is +54, it is obvious that the addition of the xylene sulfonate to a normally ineifectively small concentration of keryl aryl sulfonate has exercised a synergistic effect sufficient to produce a solution of good detergency.

In additional tests, carried out under launderometer conditions slightly different from those described above, compositions containing and respectively, of composition A, and 90% and 80%, respectively, of composition B, were compared for detergency characteristics. The composition containing 10% of composition A, and thus only 4% of keryl aryl sulfonate, was found to be only slightly inferior to the composition containing 20% of composition A.

Components preferably employed according to our invention are: keryl aryl sulfonates having a benzene or toluene nucleus and having 12 to 16 carbon atoms in the alkyl side chain which is only slightly branched or unbranched; xylene sulfonates comprising a major portion of the sulfonate of meta-xylene, which may be segregated from spent caustic previously contacted with hydrocarbon conversion products containin xylenes; and sodium sulfate as the inorganic ingredient.

The proportions of these ingredients preferably used will depend to some extent on the specific use contemplated for the product. In some applications the use of a relatively larger amount of the keryl aryl sulfonate may be justifled, whereas in others the lowest possible amount of the keryl aryl sulfonate, namely as little as 4 to 8 per cent, may be desired to produce a very inexpensive detergent of good detergency. The amount of xylene sulfonates in the preferred composition is adjusted so that the total concentration of alkyl aryl sulfonates, including the xylene sulfonates, amounts to 40 to 60 weight per cent.

The compositions of the present invention ordinarily will comprise: from 4 to 35 weight per cent of an alkali metal alkyl aryl sulfonate having from 9 to 16 carbon atoms in the alkyl side chain; from 10 to 60 weight per cent of xylene sulfonates;

and from to 60 weight per cent of a water solu- V ble alkali metal salt such as the sodium, potassium, and lithium sulfates, sulfites, thiosulfates, chlorides, dihydrogen phosphates, borates, and acetates, but preferably an alkali metal sulfate. In illustration of the compositions in accordance with the present invention, the ingredients may be present in the following distribution:

alkali metal keryl aryl sulfonate: alkali metal xylene sulfonate: alkali metal sulfate== 5:50:45 or 10:40:50 or 10:20:60.

The nature and objects of the present invention having been fully described and illustrated, what we wish to claim as new and useful and to secure by Letters Patent is:

1. A composition adapted for use as a detergent which consists of from 10 to 60 weight per cent of alkali metal salts of xylene sulfonic acids, from 4 to weight per cent of alkali metal salts of alkyl aryl sulfonic acids having from 9 to 16 carbon atoms in the alkyl side chain, and from 30 to 60 weight per cent of a water soluble inorganic alkali metal salt.

2. A composition in accordance with claim 1 in which the alkali metal is sodium.

3. A composition in accordance with claim 1 in which the alkali metal is potassium,

4. A composition in accordance with claim 1 in which the alkali metal is lithium.

5. A composition in accordance with claim 1 in which the xylene is meta-xylene.

6. A composition in accordance with claim 1 in which the water soluble alkali metal salt is sodium sulfate.

'7. A composition in accordance with claim 1 in which the alkyl aryl sulfonates are alkyl benzene sulfonates having from 12 to 16 carbon atoms in the alkyl side chain.

8. A composition in accordance with claim 1 in which the alkyl aryl sulfonates are alkyl toluene sulfonates having from 12 to 16 carbon atoms in the alkyl side chain.

9. A composition adapted for use as a detergent which consists of from 40 to weight per cent of sodium salts of xylene sulfonic acids, from 8 to 12 weight per cent of sodium salts of alkyl aryl sulfonic acids having from 12 to 16 carbon atoms in the alkyl side chain, and from 38 to 52 weight per cent of sodium sulfate.

10; A composition adapted for use as a detergent which consists of 48 weight per cent of sodium salts of xylene sulfonic acids, the preponderant portion of which is derived from meta-xylene, 8 weight per cent of sodium salts of alkyl benzene sulfonic acid having from 12 to 16 carbon atoms in the alkyl side chain, and 44 weight per cent of sodium sulfate,

JERE C. SHOWALTER. .ALBERT J. SHMIDL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,531,328 Wotherspoon Mar. 31, 1925 1,883,860 Bertsch Oct. 25, 1932 2,071,512 Ellis Feb. 23, 1937 2,161,174 Kyrides June 6, 1939 2,387,572 F'lett Oct. 23, 1945 FOREIGN PATENTS Number Country Date 146,223 Great Britain 1922 

1. A COMPOSITION ADAPTED FOR USE AS A DETERGENT WHICH CONSISTS OF FROM 10 TO 60 WEIGHT PER CENT OF ALKALI METAL SALTS OF XYLENE SULFONIC ACIDS, FROM 4 TO 35 WEIGHT PER CENT OF ALKALI METAL SALTS OF ALKYL ARYL SULFONIC ACIDS HAVING FROM 9 TO 16 CARBON ATOMS IN THE ALKYL SIDE CHAIN, AND FROM 30 TO 60 WEIGHT PER CENT OF A WATER SOLUBLE INORGANIC ALKALI METAL SALT. 